Electrical Preventive Maintenance and Testing on Circuit Breakers Maintenance - Report Example

AADC Visit: Electrical Preventive Maintenance and Testing on Circuit Breakers Maintenance Author’s name Institutional affiliation Abstract Electrical Preventive Maintenance & Testing (EPMT) provides proactive response to possible equipment failures. In this report, I document the findings from a visit we carried out at AADC on Tuesday 6th November, 2012 to seek understanding of their strategies with bias to circuit breakers maintenance. The report is informed by ELT N301 - Electrical Testing and Maintenance combined with analysis and correlation between it and the industry practice. AADC visit: Electrical Preventive Maintenance and Testing on Circuit Breakers Maintenance Introduction We had none of us familiar with neither AADC operation nor anyone who could link us up with it. Thanks to online presence, we quickly searched for and got the company contacts. I made phone calls and e-mail communications to arrange for a preliminary visit. The reconnaissance came just a week to our scheduled visit. Karl and I met Mr. Wright, the Manager- Electrical Distribution and we drafted a program for our intended visit on 6th November, 2012. Each of us took a copy and Karl too remained with one. The program covered key areas of discussion and task allocations. Precisely, it captured introductions of participants, electrical distribution process and safety in electrical distribution environment. We emphasized also included circuit breakers maintenance. Additional details were to be made upon visit. Mr. Wright promised to take us through basic maintenance of circuit breakers in their laboratory. He wondered if we needed to carry our laboratory coats, but we agreed he would lend us for the visit. On the material day my team set off to AADC and arrived at 9:30 am. We were warmly welcomed by two support engineers before they ushered us in the electrical department. The environment had already been set up for our visit and we were taken around the department. We saw some of the awards of honor the department had acquired from electricity regulatory bodies, and municipality for its exemplary supply of power in the public. Mr. Wright then came and we began formal sessions with regard to the program of visit. We sat at a round table as he led us in introduction and review of responsibilities then we delved in the subject matter. The department of Electrical Distribution has a staff of forty. It is tasked with the wholesome responsibility to research, coordinate, oversee, and conduct maintenance of the company electrical power supplies to the citizenry. The annual target is two million new connections to the public. The department has a short term strategic plan to put up five new substations and construct high voltage power lines transcending 1000 kilometers. The biggest challenge it faces is vandalism of electrical equipment in the unsecured neighborhoods. This leads to cost overruns and eats into their profits. Distribution Maintenance strategies Large companies like AADC have built strong reputations and customer loyalties that keep attracting more clients for their expansion. The cost of failure is so great that they invest heavily in maintenance strategies geared. Great effort is employed to avoid failure or mitigate its impact if it has to occur. Proactive maintenance is paramount to keep operations at all time high for profitability in such companies[Phi03]. Large companies must closely monitor their equipment and trend their performance. This is the way to keep up their brand. Proactive maintenance encompasses predictive and preventive maintenance. Predictive maintenance keeps track of equipment deteriorate ion as measured by relevant indicators. Failure modes observed say in irregular noise from a fun cooling of an electrical component infers declining efficiency. Thus, predictive maintenance is non-intrusive hence introduces no defects in the component. It does not directly alter equipment operation but provides metrics that inform corrective actions of different noted failure mechanisms. It’s important for maintenance staff to understand existing failure mechanisms which bring about deterioration fronting the failure modes. Preventive strategies tend to fix failure modes of deteriorated component. It puts in place components that meet required performance standards to minimize probability of failure. A capacitor that discharges in half desired time portends a risk that is best avoided by replacing it with a new one. This is essential to avert failure by taking corrective measures before the potential to failure escalates to real vulnerability. Simple, neglected exposures in equipment can quickly turn disastrous. Preventive strategies should be updated and documented regularly. Perfect prevention is not feasible; companies must have contingency maintenance plans. Therefore, reactive maintenance strategies should also be in place to cope with unexpected failure that may occur. The cost of proactive maintenance may seem high but the benefits are much more than the cost of fixing failures. The time to recover from a failure can lower productivity of large companies and cause them to lose their niche market to competitors. Recovery may demand product reengineering and renewed aggressive customer attraction strategies, all coming at additional operational expenditures. Large companies such as AADC should have emergency response team to counter at early stages, unforeseen electrical malfunctions that may occur to minimize interruptions of power supply and potential damages to equipment. EPMT program  Electrical Preventive Maintenance and Testing strategies improve asset life time and performance during its utilization [Ass10]. EPMT establishes acceptable system states that must be maintained for desired production or service delivery to be realized. The equipment manual is a prime document of reference in EPMT. It provides operational and maintenance steps applicable to a particular equipment including favorable environmental settings for maximum output. Equipment testing should follow industry standards. All new electrical equipment must be tested for functionality and other performance indicators that necessitated its acquisition. Preventive maintenance and testing of electrical equipment reduces unusual system breakdowns. Positive test results of control components build user confidence in using the equipment. This eliminates anxiety that can result in erroneous user activities leading to incorrect system states. The root causes of all failures observed should be analyzed and be documented for future maintenance routine. Appropriate plans must be in place to avail spares of components such as fuses that record high rates of breakdown. All equipment drawn from inventory for repair must be duly issued and recorded. The benefits of EPMT justify the cost of consistently running it. Asset protection due to EPMT, for example not only boosts equipment safety but also lengthens their smooth operation. Companies that practice EPMT have elevated system availability and enhanced production rates for better profitability. Well maintained components save energy costs and operational expenditures. Insurance costs on such equipment attract low premiums due minimal risk exposure. Computerized Maintenance Management System is fast becoming the preferred strategy to large companies like AADC.CMMS is a “one stop shop” with state-of-the -art technology to monitor and profile system status and all maintenances carried out readily accessible to authorize personnel [Kis06]. CMMS is the maintenance equivalence of Enterprise Resource Plan in managing business processes in commercial set ups. Some common CMMS features are root cause of failure analysis, asset management, and analysis of performance trending. Other features include work break-down structures, classification of critical components and inventory control. The distributed nature of CMMS, coupled with its reliable system performance metrics is essential in planning proactive maintenance. CMMS is therefore a significant quality strategy that AADC should exercise to match changing operating environments and production trends. Additionally, independent CMMS experts should be engaged to carry out unbiased preventive maintenance and testing of electrical equipment. Maintenance strategy of circuit breakers AADC has different types of circuit breakers to protect its electrical distribution systems from damage due to over currents or short circuits. A circuit breaker has five basic parts a, trip unit, terminal contacts, operating mechanism, an interrupting structure, a frame to enclose the components. The trip unit senses unusual current flow and regulates the operating mechanism. The operating mechanism opens or closes the terminal contact to protect connected equipment from power surge. The interrupting structure comprises arc chutes and all parts that carry current but the trip unit. Most circuit breaker can be observed externally through a window on their compartments. A well maintained circuit breaker should be able to sense and measure current that flows in the circuit. It should as compare the measured current value against its pre-set threshold. Once the trip point is achieved, it should open the circuit quickly in predetermined interval of time to control amount of energy flow. The insulation resistance on current carrying components under disconnected line and load conductors should be above 1 meg-ohm for safe operation. The maintenance of circuit breakers is importance for their effective performance in switching and protection of connected equipment. Failure of circuit breakers can easily result in electrical distribution system breakdowns and destroy equipment worth fortunes for a large company of AAD caliber necessitating routine maintenance. Although circuit breakers may stay idle with open or closed contacts for a long time, this must never cause delayed maintenance. Normal operation exercises the circuit breakers and lubricates it. To compensate for idle state running into months, the contacts should be opened and closed in successions to verify their correct operation. Preventive maintenance of circuit breakers includes checking for loose connections, wrong terminations, improper or dirty contacts, distorted sockets or plug-in tabs. These are undesirable states that can increase resistance, lead to overheating resulting in component deterioration and should be rectified. Repaired parts should be tested independently before they are put back to use. The arc interrupters are important in cooling and dispersion of arc flame. They should be cleaned, checked for any physical damage and subjected to high alternating current potential test across the chute. The logarithmic operation characteristics of the over current relay, which supports the tripping operation of circuit breaker, should be analyzed in terms of time and operating current. Breaker setting can be done to adjust the relay to optimal current values and response time. The planning and implementation of maintenance tasks on circuit breakers requires major safety considerations. Maintenance personnel should be adequately briefed prior to the maintenance exercise, on possible hazards that may occur and applicable safety measures that must be observed. The AADC implements the National Electrical code requirements for circuit breakers that include installation of feeder, main and the branch circuit breakers in allocation that is readily accessible. It also defines clear marking of breaker on and off position. Generally the breaker is clearly marked to enable easy reading of the amperage rating after installation. Wires connected to the breaker must be fitted appropriately to the breaker’s terminal contacts[Kei98]. Additionally, a working space as wide as equipment, or no less than 30 inches wide and 3 feet in depth, or at least deep enough to let any door to open at a right angle in front of the component enclosing the breaker. Only duly qualified and authorized personnel should conduct the maintenance with the relevant tools putting on proper protective gear Summary The visit at AADC was a great success. It gave us an eye opener in creating important industry link. By end of it, we could trace real industry application of the electrical preventive maintenance and testing skills and knowledge we learnt in the course work. Mr. Wright and his team were so friendly and technically. They easily communicated technical details in simple language. The circuit breaker maintenance processes in the laboratory was particularly intriguing. Conducting such visits at least once in a semester would highly improve our skills. Moreover, it would help us gain basic experience on the actual industry processes in electrical distribution systems. The department should create many such liaisons with relevant companies in electricity supply. This would equip learners with strong skills and build their confidence in handling technical maintenance procedures in production environments. Finally, they can comfortably adopt technological trends in the current market to create jobs and to boost the economy. . References Phi03: , (Kiameh, 2003), Ass10: , (Association, 2010), Kis06: , (Bagadia, 2006), Kei98: , (Harker, 2007), Read More